Senate Republican leaders are trotting out their new, but reeling, health care bill and angling toward a showdown vote next week amid signs that they have lots of work ahead to win over GOP lawmakers or face a resounding failure.

Senate Majority Leader Mitch McConnell, R-Ky., planned to present the revamped measure rolling back much of President Barack Obama’s health care law to GOP senators Thursday. He’s aiming at a do-or-die vote next week on whether to begin debating the bill — a roll call for which he’s got no margin for error.

Since Democrats uniformly oppose the effort, McConnell needs the votes of 50 of the 52 GOP senators to prevail. But conservative Sen. Rand Paul of Kentucky says he’s a “no,” Maine moderate Susan Collins seems all but certain to be opposed and other Republicans are threatening to vote against it if their demands are not met, leaving party leaders struggling to preserve one of their highest-profile priorities.

“It’s going to be a test of our ability to actually embrace progress, even though it’s not perfect,” said No. 2 Senate Republican leader John Cornyn of Texas.

President Donald Trump heaped additional pressure on party leaders Wednesday. In an interview with the Christian Broadcasting Network’s “The 700 Club,” he said he will be “very angry” if the Senate fails to pass the health care measure and said McConnell must “pull it off.”

McConnell’s new bill was expected to offer only modest departures from the original version, which he yanked off the Senate floor two weeks ago to avoid certain defeat at the hands of a broad range of unhappy Republicans.

The reworked measure’s key elements remain easing Obama’s requirements that insurers cover specified services like hospital care and cutting the Medicaid health care program for the poor, disabled and nursing home patients. Obama’s penalties on people who don’t buy coverage would be eliminated and federal health care subsidies would be less generous.

The new package would keep most of the original bill’s Medicaid reductions and eliminate tax increases Obama’s statute imposes on the health care industry. But it would retain Obama tax boosts on upper-income people, and use the revenue to help some lower earners afford coverage, provide $45 billion to help states combat drug abuse and give extra money to some hospitals in states that didn’t use Obama’s law to expand Medicaid.

Collins has long complained the measure will toss millions off coverage. Spokeswoman Annie Clarke said Collins would vote no next week “if the Medicaid cuts remain the same” as those that have been discussed.

Besides Paul and Collins, at least three other Republican senators publicly said they hadn’t decided whether to back McConnell on the initial vote: conservative Sens. Ted Cruz of Texas, Utah’s Mike Lee and Tim Scott of South Carolina.

Cruz and Lee are chief authors of a proposal that would let an insurer sell low-premium, bare-bones policies as long as the company also sold a plan covering all the services — like substance abuse treatment — required by Obama’s law.

Their plan has alienated moderates worried it would mean unaffordable coverage for people with serious medical conditions because healthier people would flock to cheaper, skimpier plans. Party leaders have not determined if the proposal will be in their measure, and there have been talks about altering it to limit premium boosts on full-coverage policies.

“If there are not meaningful protections for consumer freedom that will significantly lower premiums then the bill will not have the votes to go forward,” Cruz told reporters.

Lee has said he wants their proposal in the bill, or something else relaxing Obama’s coverage requirements, for him to support it.

Their proposal endured a blow when the insurance industry’s largest trade group, America’s Health Insurance Plans, said it would lead to “unstable health insurance markets” and said people with serious pre-existing medical conditions could “lose access” to comprehensive or reasonably priced coverage.

Scott said he was still trying to determine if the legislation would help families and consumers with pre-existing medical problems.

Sen. Rob Portman, R-Ohio, who has fought to ease the bill’s Medicaid reductions, has also yet to commit to back the measure next week.

McConnell withdrew an initial package two weeks ago in the face of Republican discord that would have spelled certain defeat.